In the event that you need to force VCS to start without some of the nodes defined to be part of the cluster, your need to perform a Manual GAB membership seeding on the node that is working.

Refer to the gabconfig man page for more details, but I am pretty sure that "gabconfig -c0" is not going to work as it does not conform the the gabconfig syntax. I thing you generally want to do "gabconfig -cx", after first making sure that there are no pre-existing network partitions.

You are correct in that if both nodes do not come up, then GAB will not seed preventing the cluster from starting (had daemon will still start, but the engine log will say VCS is waiting for GAB membership.

You used to be able to use "gabconfig -cx" to manually seed, but now (since about 6.0 I think) you have to use "gabconfig -x" (which works on previous versions of VCS too), otherwise you get "Gab already configured message".